The invention relates to a support device for the human vertebral column.
DE-GM 8,711,317 discloses a support device for the vertebrae of the human vertebral column in which so-called Schanz screws are screwed via the pedicles into the vertebra body. Said screws are received in holding bushes which are mounted rotatably in holding bodies. The holding bodies in turn can be screwed onto the end of a threaded bolt. The known supporting device permits an adjustment of the Schanz screws in three degrees of freedom; it can therefore not only be screwed at the correct angle into the arch foot but also permits thereafter a free movement in space in order for example to adjust two vertebrae with respect to each other in a desired manner. This is for example necessary to carry out a reduction of vertebrae and/or relieve a fractured vertebra from the adjacent vertebrae. However, the known support device is not able to bridge more than one vertebra or to ensure a multisegmentary repair for instance in the case of so-called layered or multilevel fractures.
It is also already known to fix pedicle screws to a thread wire. The pedicle screws have a forked head which comprises two cylindrical bore portions which are spaced by a web and open towards the fork opening and into which the cylinder portions have nuts which are screwed onto the thread wire can be introduced. With the aid of two nuts a pedicle screw can be fixed both in the axis position on the wire and in its rotational position on the thread or screw wire. With the aid of such a support device, in which the thread wire is implanted dorsally, pedicle screws can be set in a number of vertebrae. However, because of inadequate strength the known support device does not provide any primarily stable support. It can therefore essentially be used only for vertical columns which are in themselves stable and the line of which is to be corrected for orthopaedic reasons. The known device is not suitable for a repair of vertebral column fractures, in particular multilevel or layered fractures.
The innovation is therefore based on the problem of providing a support device for the human vertebral column with which more than one vertebra can be bridged and which permits a primary stabilization of the vertebrae with respect to all degrees of freedom.
This problem is solved according to the invention by the features of the apparatus of the invention.